Co-owned U.S. Pat. No. 3,247,852 discloses an inexpensive, disposable, and widely used umbilical cord clamp for closing the umbilical cord of a newborn infant. The clamp is formed of flexible plastic, has a pair of arms joined by an integral hinge, and is provided with locking means in the form of a hook portion 16 receivable in a recess 18 when the clamp is closed (FIG. 2).
Despite the effectiveness of the clamp disclosed in the aforementioned patent, the device lacks visual means for clearly indicating to a user that complete latching or locking has occurred. FIG. 2 of the patent depicts hook 16 as being fully inserted in recess 18. While that is the fully latched condition of the hook when the clamp is closed, the fact remains that a user, without the benefit of the sectional view of FIG. 2, looking only at the outer surfaces of the closed clamp, could not easily determine with certainty that the hook is fully received within the recess instead of being only partially received within that recess.
It is therefore an object of this invention to provide an umbilical cord clamp equipped with a lock construction that provides a clear visual (also audible) indication to a user tha the parts are completely locked together. In addition, it is an object to provide a clamp having arms which lock together even more securely under conditions which distort the arms, that is, under conditions which cause an outward bowing of the arms by reason of the cord clamped therebetween. A particularly important aspect of the invention lies in providing a latching or locking mechanism which provides exceptional security without requiring increased closing force for its operation. The force required to close a clamp embodying this invention is in fact reduced without any sacrifice in security and with the advantages of clear visual and audible indications of latch operation.
Briefly stated, the clamp is of generally V-shaped configuration and has a pair of flexible arms with rear end portions joined together by an integral hinge at the apex of the V-shaped clamp. The free forward ends of the arms are normally disposed in spaced relation and are movable towards each other for the purpose of clamping an umbilical cord between the arms. The locking means for securing the arms together takes the form of a flexible tongue at the forward end of one of the arms, the tongue projecting towards the other arm in the direction of locking movement of the first arm. The other arm, or second arm, has a forwardly-facing recess at its free end for receiving the tongue. A pair of projections extend into the recess from opposite sides thereof, such projections having forwardly-sloping ramp surfaces which are engagable with the tip of the tongue for flexing that tongue forwardly as the clamp is squeezed into partially closed condition. The tongue has a pair of lateral notches which are spaced from the tip for receiving the projections after the tongue has cleared the ramp surfaces and has snapped rearwardly into an unflexed and untensioned locking condition. With the tongue in that condition, the side projections are clearly visible, and preferably protrude slightly forwardly through, the lateral notches of the tongue to provide a clear visual indication that the arms are fully locked together.
As the elongated tongue snaps into its locking position, it engages the other arm with a forceful snap or click, thereby giving an audible signal that locking or latching has occurred. Further security is achieved by reason of the fact that outward bowing of the arms tends to force the latched tongue rearwardly into even greater latching engagement with the lateral projections. In the preferred embodiment disclosed herein, a slight spacing may be provided between the rear surface of the recess and the tongue when the clamp is closed without appreciable bowing of the arms, such space thereby accommodating limited additional rearward displacement of the tip portion of the tongue when the clamp is closed under conditions which cause substantial outward bowing of such arms. Under extreme conditions, as where arm distortion is so great that the tongue is forced to bend in its latched or locked condition, such bending action enhances rather than reduces the security of the interlocking relationship.
Other features, advantages, and objects of the invention will become apparent from the specification and drawings. For a more complete understanding of the state of the prior art, reference may be had to U.S. Pat. Nos. 3,854,482, 3,735,765, and 3,822,052.